Environment control device for electrophotographic apparatus

ABSTRACT

Moisture content of receiver material is controlled within an electrophotographic apparatus by providing one or more heaters in proximity to a supply of receiver material which heaters heat the surrounding air in response to a humidistat control to keep the humidity from exceeding a predetermined level. One of the heaters is arranged to heat both the supply of receiver material and a paper feed path along which the material is fed from the supply. Thus, paper which remains in the feed path when the machine is not operating will be maintained at the correct moisture content.

United StatesjPatent MacDonald, Jr.

[451 July 18,1972

[54] ENVIRONMENT CONTROL DEVICE FOR ELECTROPHOTOGRAPHI APPARATUS [72]Inventor; William A. MacDonald, Jr., Rochester, N.Y.

Eastman Kodak Company, Rochester, .N.Y.

22 Filed: Sept. 10, 1970 211 Appl.No.: 71,163

[73] Assignee:

[52] U.S. Cl. [51] Int. Cl. [58] Field of Search "95/89, 92, 94, 90;355/3 [56] References Cited UNITED STATES PATENTS 3,349,221 10/1967Schulze et al ..2l9/385 3,072,026 1/1963 Mackrodt ..355/l2 PrimaryExaminer-John M. l-loran Assistant Examiner-Kenneth C. HutchisonAttorney-Robert W. Hampton and Gary D. Fields 57] ABSTRACT Moisturecontent of receiver material is controlled within an electrophotographicapparatus by providing one or. more heaters in proximity to a supply ofreceiver material which heaters heat the surrounding air in response toa humidistat control to keep the humidity from exceeding a predeterminedlevel. One of the heaters is arranged to heat both the supply of Ireceiver material and a paper feed path along which the material is fedfrom the supply. Thus, paper which remains in the feed path when themachine is not operating will be maintained at the correct moisturecontent.

4 Claim, 3 Drawing Figures Patented July 18,1972

- 2 Sheets-Sheet lv FIG. 3

WILLIAM A. MOCDONALD,JR. INVENTOR 1w BYWW. W

ATTORNEYS Patented July 18, 1972- 2 Shets-Sheet z 3 ll :11 I1 1 I 1 bl.3w...- 8

4 x 3 I1 w A n m n 2 II! FIG. 2

WILLIAM A. MOCDONALD,JR.

INVENTOR. BY (9. 54%

ATTORNEYS ENVIRONMENT CONTROL DEVICE FOR ELECTROPIIOTOGRAPIIIC APPARATUSBACKGROUND OF THE INVENTION 1 Field of the Invention This inventionrelates to a humidity control device, and more particularly to ahumidity control device for use in an electrophotographic apparatus.

2. Description of the Prior Art In one form of electrophotographicapparatus, an electrophotographic image is placed on a receiver materialhaving a conductive backing and a photoconductive surface, such as azinc oxide, upon which the image is placed. This material is I fed froma supply along a feed path to a charging station, such electrostaticcharge on the photoconductive surface. Also, the

material is cut to a sheet of desired length. The charged sheet is fedto an exposure station where it is exposed to a light pattern whichcauses the photoconductive surface to be discharged in the exposed areaswhile retaining an electrostatic charge in the charged areas to form anelectrostatic charge pattern. The photoconductive sheet is then fed to adeveloping station where toner particles of opposite charge to theelectrostatic charge pattern are attracted thereto to form a toner imageon the pho toconductive surface. The sheet then passes through a fusingstation to cause the toner image to adhere tothe receiver sheet to forma permanent copy.

However, under high humidity conditions, the resistivity of the receivermay be decreased to a level which results in an image of reduced qualitybecause of an increase in the relative humidity thereof. This isparticularly true when the apparatus is idle for extended periods oftime, such as overnight or over a weekend. In such situations, thesupply of receiver material,

and especially the receiver material which remains in the feed path willbe affected by the ambient humidity conditions. Thus, if the relativehumidity is high, the moisture content of the receiver, both in thesupply and in the feed path, may increase to an undesirably high levelwhich adversely effects the charge-holding characteristics of thereceiver.

The problem of humidity control was recognized in U.S. Pat. No.2,885,556 to Gundlach who shows a method of increasing the moisturecontent of the paper but does not suggest decreasing the moisturecontent thereof.

In U.S. Pat. No. 3,072,026 to Mackrodt an electrophotographic device isshown which has heating elements in the feed path for zinc oxidephotoconductive material to dry it out as it is fed to a chargingstation to thereby reduce the moisture content thereof.

A humidity-controlled storage compartment is shown in U.S. Pat. No.3,349,221 to Schultze et al. for controlling the moisture content of astack of cut electrophotographic receiver sheets. A heating element isprovided in a hinged cover which is controlled by a humidistat tocontrol the relative humidity within the compartment.

I SUMMARY OF THE INVENTION In accordance with the present invention, ahumidity control device is provided adjacent a support for receivermaterial to be fed along a feed path which includes a heating meanswhich provides a dual function of heating the supply and heating thefeed path so that the moisture content of the material can be controlledboth at the supply and along the feed path. The heating means can becontrolled by a humidistat so that it goes on only when the relativehumidity rises above a predetermined level and turns off when therelative humidity drops below a predetermined level. Optionally, asecond heater can be provided on the opposite side of the supply toassure a uniform relative humidity level all around the supply. Also,thermostats can be provided for controlling of the heaters.

Additional advantages of this invention will become apparent from thedescription which follows, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTIn accordance with this invention, a reader-printer R is illus- 'tratedin FIG. 1 which is provided with a print module P, as

shown. The reader has means for projecting an image of an original, suchas microfilm 2, onto a viewing screen 4. If a print of a particularoriginal is needed a print button on control panel 6 may be pressed tocause the image to be projected onto a charged sheet of photosensitivematerial supplied from roll 8. The printer P is mounted in a drawer 10which is movable from the open position shown in FIG. 1 to a closedposition in which switch 12 is closed to cause thehumidity controldevice to operate as will be more fully understood from the descriptionbelow.

As best seen in FIG. 2, supply roll 8 is supported on a shaft 14extendingthrough spaced side plates 16 of printer module P. The paper isfed from the roll under a bail l8 and over a roller 20 and along a feedpath defined by a pair of opposed feed rollers 22 and 24.

It has been found that in high humidity environments, the

- humidity may adversely effect the photoconductive paper'9 on thesupply rolland which may tend to curl if it becomes too moist andfurthermore becomes too conductive to function properly. To avoid this,a heater 26 is provided on a baffle plate 28 between the supply roll andthe feed path provided by rollers 22 and 24 and is connected in serieswith a thermostat 30 to prevent the baffle plate from overheating. Thus,the heater 26.serves the dual function of heating supply roll 8 and alsoheating the feed path so that the moisture content of the paper can bemaintained within predetermined limits. A second heater element 32 isprovided on a baffle plate 34 mounted below supply roll 8 and connectedto a thermostat 36 mounted on the baffle plate 34. A humidistat 38,shown in FIG. 2 as being mounted on back wall 40 of the reader-printeras by a bracket 42, opens the circuit to the heaters so that they nolonger operate if the humidity level of the ambient air drops below somepredetermined level, such as 37 percent. On the other hand, when thehumidity level of the ambient air exceeds a predetermined level, say 53percent the heaters will be energized.

A completed copy 44 from the printer module P is fed between spacedguide plates 46 and 48 for feeding the copy by means of a conveyor C toa discharge chute, of FIG. 1. Conveniently, conveyor C includes a plate48 removably mounted on spaced pins 52 by brackets 54, as shown in FIG.2, so that it can be removed by the operator to correct paper jams.However, when plate 48 is removed it is desired that the heater beturned off so that the operator wont burn his hands on plate 34 and forthis purpose a switch 56 is provided which is illustrated as beingmounted on backwall 40 by means of an angle bracket 58 and is closed bymeans of an ear 60 on plate 48.

The circuitry for the humidity control device is shown in FIG. 3. Inaddition to the elements previously described, standby switch 62 isprovided which is shown as being mounted adjacent roll 8 in FIG. 1 andis controlled by the operator to turn off the humidity control device,if desired. Standby switch 62 is a double pole switch, as shown in FIG.3, having one side connected to one side of a source of potential andthe other side connected in series with door operated switch 12, chuteoperated switch 56, and humidistat 38. Also connected in series is aswitch 64 which is opened by current through coil 66 when the printmodule P is in operation to discontinue operation of the heater duringthe print cycle. This is desirable to reduce the total powerrequirements of the apparatus. The opposite side of switch 64 isconnected to the opposite side of the source of potential. Double pullswitch 62 also is connected to opposite sides of the heaters andthermostats, as shown.

From the foregoing, the advantages of this invention are readilyapparent. A humidity control device has been provided which includesheating elements to maintain relative humidity within a predeterminedrange so that the moisture content of the receiver is neither too highnor too low, Furthermore, one heater is advantageously positioned toserve the dual function of heating the supply of photoconductivematerial and heating the feed path along which the material is fed fromthe supply roll. This is advantageous when the apparatus has been idlefor some period of time, such as overnight or over a weekend since aportion of the photoconductive sheet 9 always extends into the feed pathand also must be maintained at the proper moisture content level alongwith the supply roll so that the first prints will be satisfactory.

The invention has been described in detail with reference to a preferredembodiment thereof, but it will be understood that variations andmodifications can be effected within the spirit and scope of theinvention.

I claim: 1. A humidity control device, having an enabled and disabledcondition, for use in an electrophotographic apparatus used undervarying relative humidity conditions for controlling the moisturecontent of photoconductive receiver material, said control deviceincluding:

a support for the supply of receiver material; means defining a feedpath for feeding the receiver material from said support; firstcontrollable means for simultaneously heating the supply on said supportand for heating said feed path; and

means responsive to operation of said electrophotographic apparatus todisable said humidity control device during such operation.

2. A humidity control device, having an enabled and disabled condition,for use in an electrophotographic apparatus used under varying relativehumidity conditions for controlling the moisture content ofphotoconductive receiver material, said control device including:

means for rotatably supporting a supply roll of receiver material;

means defining a feed path for feeding the photoconductive material fromsaid supply roll;

a first baffle plate mounted between said support and said feed pathdefining means for heating both said supply roll and said heat path;

a first controllable heater mounted on said first baffle for heatingsaid first baffle plate;

a first thermostat mounted on said first baffle plate and connected tosaid heater for controlling the temperature of said first baffle plate;

a second baffle plate spaced from said first baffle plate with saidsupport therebetween;

a second controllable heating means mounted on said second baffle platefor heating said second baffle plate;

a second thermostat mounted on said second baffle plate and connected tosaid second heating means for controlling the temperature of said secondbaffle plate.

3. A humidity control device, as claimed in claim 2, further including:

means responsive to operation of said electrophotographic apparatus todisable said humidity control device during such operation.

4. A humidity control device, as claimed in claim 2, further including:

a humidistat mounted adjacent said support and said feed path definingmeans and connected to said heating means to control said heating meansin response to relative humidity.

1. A humidity control device, having an enabled and disabled condition,for use in an electrophotographic apparatus used under varying relativehumidity conditions for controlling the moisture content ofphotoconductive receiver material, said control device including: asupport for the supply of receiver material; means defining a feed pathfor feeding the receiver material from said support; first controllablemeans for simultaneously heating the supply on said support and forheating said feed path; and means responsive to operation of saidelectrophotographic apparatus to disable said humidity control deviceduring such operation.
 2. A humidity control device, having an enabledand disabled condition, for use in an electrophotographic apparatus usedunder varying relative humidity conditions for controlling the moisturecontent of photoconductive receiver material, said control deviceincluding: means for rotatably supporting a supply roll of receivermaterial; means defining a feed path for feeding the photoconductivematerial from said supply roll; a first baffle plate mounted betweensaid support and said feed path defining means for heating both saidsupply roll and said heat path; a first controllable heater mounted onsaid first baffle for heating said first baffle plate; a firstthermostat mounted on said first baffle plate and connected to saidheater for controlling the temperature of said first baffle plate; asecond bAffle plate spaced from said first baffle plate with saidsupport therebetween; a second controllable heating means mounted onsaid second baffle plate for heating said second baffle plate; a secondthermostat mounted on said second baffle plate and connected to saidsecond heating means for controlling the temperature of said secondbaffle plate.
 3. A humidity control device, as claimed in claim 2,further including: means responsive to operation of saidelectrophotographic apparatus to disable said humidity control deviceduring such operation.
 4. A humidity control device, as claimed in claim2, further including: a humidistat mounted adjacent said support andsaid feed path defining means and connected to said heating means tocontrol said heating means in response to relative humidity.